US4269416A - Head shell for record player tonearms - Google Patents
Head shell for record player tonearms Download PDFInfo
- Publication number
- US4269416A US4269416A US06/063,532 US6353279A US4269416A US 4269416 A US4269416 A US 4269416A US 6353279 A US6353279 A US 6353279A US 4269416 A US4269416 A US 4269416A
- Authority
- US
- United States
- Prior art keywords
- head shell
- composite material
- graphite
- head
- shell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 40
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 19
- 239000010439 graphite Substances 0.000 claims abstract description 19
- 239000002131 composite material Substances 0.000 claims abstract description 17
- 239000002245 particle Substances 0.000 claims abstract description 16
- 229920005992 thermoplastic resin Polymers 0.000 claims abstract description 7
- 238000004898 kneading Methods 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims description 7
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 7
- 239000004800 polyvinyl chloride Substances 0.000 claims description 7
- 229920001577 copolymer Polymers 0.000 claims description 4
- 238000005096 rolling process Methods 0.000 claims description 4
- 229920001328 Polyvinylidene chloride Polymers 0.000 claims description 2
- 229920002433 Vinyl chloride-vinyl acetate copolymer Polymers 0.000 claims description 2
- 239000005033 polyvinylidene chloride Substances 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 9
- 238000003763 carbonization Methods 0.000 description 8
- 229920005989 resin Polymers 0.000 description 8
- 239000011347 resin Substances 0.000 description 8
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 7
- 229910052719 titanium Inorganic materials 0.000 description 7
- 239000010936 titanium Substances 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000011872 intimate mixture Substances 0.000 description 5
- 239000011159 matrix material Substances 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 241001422033 Thestylus Species 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 238000005087 graphitization Methods 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 241001274658 Modulus modulus Species 0.000 description 1
- 101100386054 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) CYS3 gene Proteins 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- -1 etc. Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920002689 polyvinyl acetate Polymers 0.000 description 1
- 239000011118 polyvinyl acetate Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 101150035983 str1 gene Proteins 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B3/00—Recording by mechanical cutting, deforming or pressing, e.g. of grooves or pits; Reproducing by mechanical sensing; Record carriers therefor
- G11B3/44—Styli, e.g. sapphire, diamond
- G11B3/46—Constructions or forms ; Dispositions or mountings, e.g. attachment of point to shank
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B3/00—Recording by mechanical cutting, deforming or pressing, e.g. of grooves or pits; Reproducing by mechanical sensing; Record carriers therefor
- G11B3/02—Arrangements of heads
- G11B3/10—Arranging, supporting, or driving of heads or of transducers relatively to record carriers
- G11B3/30—Supporting in an inoperative position
- G11B3/31—Construction of arms
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/16—Mounting or connecting stylus to transducer with or without damping means
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/30—Self-sustaining carbon mass or layer with impregnant or other layer
Abstract
A head shell for a record player tonearm comprises a composite material essentially consisting of a thermoplastic resin and graphite powder. The composite material is prepared by kneading the components, rolled to impart a degree of orientation to the graphite powder particles, which are in the form of flaky graphite and then molded into a shell, along the surface of which the graphite particles are oriented. Head shells wherein the composite material is oxidized at the surface and head shells wherein the composite material is carbonized or graphitized are also included. A light weight, rigid head shell having a high specific modulus of elasticity is obtained through a simple procedure at low cost.
Description
This invention relates to head shells for record player tonearms.
The recent trend of tonearms for record players is directed toward a reduction of the mass and an increase of the compliance of a vibration system in order to enhance the trackability of a cartridge.
With the compliance of a cartridge increased, the low range resonance frequency attributable to the cartridge compliance and the equivalent mass of a tone arm (including the cartridge) at the stylus tip is reduced such that noise signals due to warpage and eccentricity of a record may be often picked up. That is, the increased compliance results in a reduced signal-to-noise ratio. It is therefore necessary to adjust low range resonance to an inoffensive level, generally to a range of 10 to 15 hertz while the stylus equivalent mass is kept low.
To reduce the equivalent mass at the stylus tip, in usual practice, tonearm component parts such as arm pipe and head shell may be reduced in weight. Parts having a wall thickness reduced for light weight exhibit a low rigidity which in turn, allows undesirable phenomena such as partial vibration to occur, resulting in deteriorated sound quality. To obtain light weight arm pipes and head shells having a high rigidity, materials are required having a high specific modulus of elasticity.
In prior art arm pipe and head shell manufacture, aluminum and titanium are used because they have a relatively high specific modulus. However, the use of a cartridge with an increased compliance requires the arm pipes and head shells to be made of material having a higher specific modulus than aluminum and titanium.
Arm pipes and head shells made of fibrous carbon are known. Fibrous carbon itself has a sufficiently high specific modulus while it cannot be formed into a part without a binder. Usually, a resin is used to bind fibrous carbon. However, the addition of a resin binder to fibrous carbon causes the specific modulus of elasticity to reduce to a level equal to or less than those of aluminum and titanium. Therefore, the fibrous carbon composite material is not satisfactory as the material for arm pipes and head shells.
Accordingly, it is an object of the present invention to provide a high performance head shell made of a light weight, rigid composite material having a high specific modulus of elasticity.
According to one aspect of this invention, there is provided a head shell for a tonearm of a record player which comprises a composite material of a thermoplastic resin and graphite powder. The material is obtained simply by kneading the components and the graphite powder particles are oriented substantially in parallel with the surface of the head shell.
According to another aspect of this invention, the material in the form of a head shell is oxidized at least at the surface. The material may also be carbonized.
To provide the graphite powder particles with a substantial degree of orientation, the kneaded mixture may preferably be rolled into a sheet before a head shell is formed therefrom.
The invention will now be described in further detail by referring to the accompanying drawings wherein:
FIG. 1 is a partial cross-sectional view of a mixture of graphite particles and a resin matrix;
FIG. 2 is a partial cross-sectional view of a sheet of a composite material wherein graphite particles are oriented in a resin matrix;
FIG. 3 is a perspective view of the head shell of the invention;
FIGS. 4 and 5 are cross-sectional views of the head shell taken along the lines IV--IV and V--V in FIG. 3, respectively; and
FIG. 6 is a schematic view of a tonearm system.
The thermoplastic resins used herein include polyvinyl chloride, polyvinylidene chloride, vinyl chloride-acrylonitrile copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, etc., and mixtures thereof. The resins may be changed into a pitch-like state by dry distillation before it is kneaded with graphite powder.
The graphite powder is available from many manufacturers. Flaky graphite is most preferable. The graphite powder may preferably have an average particle size of less than 20 microns (inclusive), particularly 0.1 to 5 microns.
The weight ratio of resin to graphite is 1:9 to 9:1, preferably 3:7 to 7:3.
An example of this invention is shown below. Polyvinyl chloride (to be abbreviated as "PVC" hereinafter) is used as a typical thermoplastic resin. In a kneader, 30 parts by weight of PVC is blended and kneaded with 70 parts by weight of graphite powder at a temperature of 130°-200° C. The green intimate mixture is further mixed and rolled into a sheet at a similar temperature. This sheet exhibits a Young's modulus E of 6,000 kg/mm2 (5.9×1010 N/m2) and a density ρ of 1.8 g/cm3. The specific modulus of elasticity calculated in terms of √E/ρ is 5.7×103 m/sec, which value is higher than the specific modulus of titanium of 5.2×103 m/sec. The green, but oriented sheet is formed into a shell though the following description omits this step for the purpose of illustrating measured values.
The rolled sheet is then subjected to presintering or oxidation by gradually heating it in an oxidizing atmosphere to a temperature of 100°-500° C., preferably 250°-300° C. at a rate of 1°-10° C./hour. The oxidized product has a Young's modulus E of 9,000 kg/mm2, a density ρ of 1.8 g/cm3 and a specific modulus √E/ρ of 7.0×103 m/sec.
The oxidized sheet is further subjected to carbonization or graphitization by heating it in a non-oxidizing atmosphere or in vacuum to a temperature of about 1200° C. or higher at a rate of 10°-20° C./hour. The carbonized sheet exhibits a Young's modulus E of 16,000 kg/mm2 and a density ρ of 1.8 g/cm3. The specific modulus of elasticity of 9.33×103 m/sec is about 2 times higher than those of aluminum and titanium. Graphitization of the sheet at about 2500° C. increases the Young's modulus 1.5 times to 24,000 kg/mm2.
Orientation of graphite powder particles is essential to achieve the above-illustrated desired values. When PVC is kneaded with graphite powder and the resulting green mixture is formed into a desired shape by extrusion, for example, without an orientation procedure, the resulting product shows a poor Young's modulus. By way of example, when 30 parts of PVC was kneaded with 70 parts of graphite powder and the mixture was then extrusion molded by means of an extruder into a plate, the plate showed a Young's modulus of about 1,300 kg/mm2. This value is less than a quarter of that of the graphite-oriented sheet described above. Further carbonization of this non-oriented plate resulted in a Young's modulus of about 4,000 kg/mm2, which valve is about 1/6 of that of the graphite-oriented one after carbonization.
Further, it has been found that the internal loss (tan δ) of the composite material according to this invention is higher than those of aluminum and titanium. The higher the internal loss, the less undesirable resonance is liable to occur.
The measurements of various properties show that the composite material of this invention has a relatively light weight, a high rigidity, a high specific modulus of elasticity, and a good internal loss.
As described above, to fabricate a head shell without impairing the characteristics of the composite material according to this invention, graphite powder particles must be oriented in the resulting head shell. In this respect, molding which is generally used in prior art manufacture it not applicable because graphite particles are not substantially oriented so that molded products are less rigid.
Referring to FIG. 1, a fragmental portion of a kneaded or intimate mixture is shown wherein a resin matrix 1 contains graphite flakes 2 at random. The graphite particles in the form of a flake may be considered as a disc having a high ratio of diameter to thickness. The intimate mixture shows a random distribution of graphite flakes 2 in the resin matrix 1.
The intimate mixture is then rolled into a sheet at elevated temperatures by means of rollers, presses or the like. FIG. 2 shows a rolled sheet 3 wherein graphite flakes 2 are oriented in parallel with the surface of the sheet 3. Rolling is a typical, but non-limiting treatment for imparting a substantial degree of orientation to graphite particles. The thickness of the rolled sheet 3 depends upon the desired wall thickness of a head shell produced therefrom.
The sheet 3 is press molded into a head shell 4 depicted in FIG. 3 by means of a suitable mold at an elevated temperature of 200° to 300° C. As shown in FIGS. 4 and 5 which are the cross-sectional views taken along lines IV--IV and V--V of FIG. 3, the graphite powder particles 2 are oriented substantially in parallel with the surface of the head shell 4. In the illustrated embodiment, a head shell is molded from a single sheet. In another embodiment, a plurality of thinner sheets may be laminated before or when a shell is molded. After molding, machining is carried out to form necessary bore and slots.
After the shell 4 shown in FIGS. 3 to 5 is formed, it is subjected to pre-sintering or oxidation by heating it in an oxidizing atmosphere to a temperature of about 250° C. at a rate of 1°-10° C./hour. Further, the shell is subjected to carbonization or graphitization by heating it in a non-oxidizing atmosphere to a temperature of 1200° C. at a rate of 10°-20° C./hour. The rigidity of the shell is increased by carbonization while the internal loss is reduced in proportion.
The shell 4 is susceptible to deformation during the pre-sintering or oxidation step. Therefore, the shell should be supported in a suitable manner, for instance, by placing it on a block (made of material not deformable at a temperature above 250° C.) or by enclosing it within a protecting support. Since the shell becomes self-supporting after the oxidation, no support is required during carbonization.
The carbonization temperature may be higher than 1200° C. The shell graphitized at a temperature of 2,500° C. is 1.5 times higher in rigidity than that carbonized at a temperature of 1,200° C.
FIG. 6 shows an entire tonearm system. The head shell 4 of this invention is mounted on an arm pipe 5, which may be fabricated of the same material as the shell. The arm pipe 5 has a counter weight 6 mounted at the opposite end and is supported by an arm support 7.
A sample was prepared by blending and kneading a polyvinyl chloride-polyvinyl acetate copolymer and graphite powder at a weight ratio of 1:2. The resulting intimate mixture was rolled to achieve a substantial degree of orientation of graphite. Measurement was made after rolling, oxidation, and carbonization. The results are tabulated below.
TABLE ______________________________________ Young's Specific Internal Density modulus modulus loss ρ(g/cm.sup.3) E (kg/mm.sup.2) ##STR1## tan δ ______________________________________ Rolled 1.8 6,000 5.7 × 10.sup.3 0.05 Oxidized 1.8 9,000 7 × 10.sup.3 0.02 Carbonized 1.8 16,000 9.33 × 10.sup.3 0.015 Aluminum 2.7 7,400 5.18 × 10.sup.3 0.003 Titanium 4.4 12,000 5.22 × 10.sup.3 0.003 ______________________________________
As understood from the foregoing, the orientation of graphite powder particles in the resinous matrix in a direction substantially parallel with the surface provides a light weight head shell having a high rigidity, that is, a head shell giving a low equivalent mass at the stylus tip. Such a head shell tends to pick up few noise signals due to warpage and eccentricity of a record and ensures reproduction at an improved S/N ratio when used in combination with a high compliance cartridge. The head shell of the invention has an internal loss such that undesirable resonance or partial vibration may not occur. Further, the composite material is readily prepared by kneading relatively inexpensive starting components, orientation is imparted by rolling or other suitable treatments, and the material is formed by a conventional method. These factors contribute to a reduction of cost.
Although the present invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will, of course, be understood that various changes and modifications may be made in the form, details, and arrangements of the parts without departing from the scope of the invention as set forth in the following claims.
Claims (8)
1. A head shell for a record player tonearm comprising a composite material essentially consisting of 10-90 parts by weight of a thermoplastic resin and 90-10 parts by weight of flaky graphite wherein the composite material is prepared by kneading the components and the graphite flakes are oriented substantially in parallel with the surface of the shell.
2. A head shell according to claim 1 wherein said composite material is oxidized at least at the surface of the shell.
3. A head shell according to claim 1 wherein said composite material is carbonized.
4. A head shell according to claim 1 wherein said shell is fabricated by kneading the components, rolling the kneaded mixture into a sheet to achieve a substantial degree of orientation of the graphite flakes, and then forming the sheet into a desired shape.
5. A head shell according to any one of claims 1 to 3, wherein said thermoplastic resin is selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, vinyl chloride-acrylonitrile copolymers, vinylidene chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate copolymers, and mixtures thereof.
6. A head shell according to any one of claims 1 to 3, wherein said graphite flakes has a particle size of 0.1 to 20 microns.
7. A head shell according to claim 6, wherein said graphite flakes have a particle size of 0.1 to 5 microns.
8. A head shell according to claim 1, wherein said composite material includes 30 to 70 parts by weight of said thermoplastic resin and 70 to 30 parts by weight of said flaky graphite.
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP53-94654 | 1978-08-04 | ||
JP9465478A JPS6053364B2 (en) | 1978-08-04 | 1978-08-04 | Head shell and its manufacturing method |
JP53-99955 | 1978-08-18 | ||
JP9995578A JPS5528512A (en) | 1978-08-18 | 1978-08-18 | Head shell |
JP16122778A JPS5589903A (en) | 1978-12-28 | 1978-12-28 | Head shell and its manufacture |
JP53-161227 | 1978-12-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
US4269416A true US4269416A (en) | 1981-05-26 |
Family
ID=27307604
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/063,532 Expired - Lifetime US4269416A (en) | 1978-08-04 | 1979-08-03 | Head shell for record player tonearms |
Country Status (2)
Country | Link |
---|---|
US (1) | US4269416A (en) |
GB (1) | GB2037053B (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4343376A (en) * | 1980-03-18 | 1982-08-10 | Pioneer Electronic Corporation | Vibratory elements for audio equipment |
US4362772A (en) * | 1980-03-31 | 1982-12-07 | Pioneer Electronic Corporation | Vibratory elements for audio equipment |
US4366205A (en) * | 1980-03-31 | 1982-12-28 | Pioneer Electronic Corporation | Tone-arm elements |
US4390382A (en) * | 1980-07-08 | 1983-06-28 | Matsushita Electric Industrial Co., Ltd. | Tone arm manufacturing method |
CN107454544A (en) * | 2017-08-15 | 2017-12-08 | 深圳清华大学研究院 | A kind of diaphragm of loudspeaker preparation method based on graphene and PEI |
CN109391880A (en) * | 2017-08-10 | 2019-02-26 | 深圳清华大学研究院 | Loudspeaker acoustic diaphragm and preparation method based on graphene REINFORCED PET plastics |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3918722A (en) * | 1973-07-09 | 1975-11-11 | Sony Corp | Tone arm |
US3923309A (en) * | 1973-07-21 | 1975-12-02 | Sony Corp | Cartridge shell for phonograph pickup |
US3957272A (en) * | 1974-04-18 | 1976-05-18 | Sony Corporation | Cartridge shell for phonograph pickup |
US3980105A (en) * | 1974-07-10 | 1976-09-14 | Hitco | Laminated article comprising pyrolytic graphite and a composite substrate therefor |
US4086378A (en) * | 1975-02-20 | 1978-04-25 | Mcdonnell Douglas Corporation | Stiffened composite structural member and method of fabrication |
US4147364A (en) * | 1977-03-30 | 1979-04-03 | Namiki Precision Jewel Co., Ltd. | Non-vibration tone arm |
-
1979
- 1979-08-03 US US06/063,532 patent/US4269416A/en not_active Expired - Lifetime
- 1979-08-06 GB GB7927324A patent/GB2037053B/en not_active Expired
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3918722A (en) * | 1973-07-09 | 1975-11-11 | Sony Corp | Tone arm |
US3923309A (en) * | 1973-07-21 | 1975-12-02 | Sony Corp | Cartridge shell for phonograph pickup |
US3957272A (en) * | 1974-04-18 | 1976-05-18 | Sony Corporation | Cartridge shell for phonograph pickup |
US3980105A (en) * | 1974-07-10 | 1976-09-14 | Hitco | Laminated article comprising pyrolytic graphite and a composite substrate therefor |
US4086378A (en) * | 1975-02-20 | 1978-04-25 | Mcdonnell Douglas Corporation | Stiffened composite structural member and method of fabrication |
US4147364A (en) * | 1977-03-30 | 1979-04-03 | Namiki Precision Jewel Co., Ltd. | Non-vibration tone arm |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4343376A (en) * | 1980-03-18 | 1982-08-10 | Pioneer Electronic Corporation | Vibratory elements for audio equipment |
US4362772A (en) * | 1980-03-31 | 1982-12-07 | Pioneer Electronic Corporation | Vibratory elements for audio equipment |
US4366205A (en) * | 1980-03-31 | 1982-12-28 | Pioneer Electronic Corporation | Tone-arm elements |
US4390382A (en) * | 1980-07-08 | 1983-06-28 | Matsushita Electric Industrial Co., Ltd. | Tone arm manufacturing method |
CN109391880A (en) * | 2017-08-10 | 2019-02-26 | 深圳清华大学研究院 | Loudspeaker acoustic diaphragm and preparation method based on graphene REINFORCED PET plastics |
CN107454544A (en) * | 2017-08-15 | 2017-12-08 | 深圳清华大学研究院 | A kind of diaphragm of loudspeaker preparation method based on graphene and PEI |
Also Published As
Publication number | Publication date |
---|---|
GB2037053B (en) | 1983-02-09 |
GB2037053A (en) | 1980-07-02 |
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